Researchers at the University of Texas have developed the first all-solid-state battery cells, capable of storing five times as much power as the current lithium-ion battery.
Leading this research is John Goodenough, co-inventor of the lithium-ion battery and professor at the Cockrell School of Engineering at The University of Texas, Austin. Goodenough partnered with Maria Helena Braga, physicist and fellow Cockrell School of Engineering researcher, to create a revolutionary, low-cost battery with the potential to store enough energy to power homes, boats, and an all-electric road vehicle, which is their first priority.
The original lithium-ion battery was created in 1980, and uses liquid electrolytes that serve as a vessel for lithium-ions traveling from the negatively-charged anode end of the battery to the positively-charged cathode end. The liquid electrolytes limit battery life and allow dendrites to form, which could result in fires or explosions if the battery short-circuits. Goodenough’s new battery uses solid glass electrolytes that improve efficiency, allow for longer battery life, and block the formation of dendrites.
After 37 years of relying on the original lithium-ion battery, many scientists in the field are skeptical of Goodenough’s new discovery. Some scientists believe that it violates the first law of thermodynamics. Dan Steingart, a professor of mechanical engineering at Princeton, goes so far as to say, “Everything I understand about chemistry and thermodynamics says this is impossible.” To his doubters, Goodenough retorts, “The skeptics do not understand the properties of an electrode/electrolyte heterojunction.”
The University Network spoke with Goodenough to address the origins of his idea, environmental benefits of the battery, and the validity of his skeptics’ claims.
TUN: Where/when did the idea for this product stem? Is this something you have had in mind since the invention of the lithium-ion battery?
Goodenough: The lithium-ion battery of your cell phone is plagued by its liquid electrolyte; it (a) is flammable, which raises safety concerns, (b) is reduced on contact with metallic lithium, which limits its charge/discharge cycle life, (c) is oxidized with a cathode voltage versus lithium that is greater than 4.3 V, (d) plates lithium on a carbon anode if charged too fast, and plating of metallic lithium from the liquid electrolyte can result in lithium whiskers (dendrites) that grow on repeated charges across the electrolyte to the cathode to create an internal short-circuit producing thermal runaway and ignition of the electrolyte. The solution to this problem is to find a solid electrolyte from which metallic lithium can be plated dendrite free and is not reduced on contact with metallic lithium. However, traditional polymer and ceramic electrolytes have too low an alkali-cation conductivity to compete with the liquid electrolyte. Our first task was to find out how to plate a dendrite-free metallic-lithium anode from a liquid, polymer, and/or solid electrolyte. I had just solved that problem when Professor Maria Helena Braga of Porto, Portugal, brought to me a remarkable glass she had prepared. Not only does her glass transport at room temperature alkali cations almost as fast as the liquid electrolyte, but it also contains a high dielectric constant indicative of the presence of electric dipoles. We quickly showed that a dendrite-free lithium anode can be rapidly plated/stripped reversibly for many thousands of charge/discharge cycles; we also showed that we can plate lithium reversibly from the anode to a copper cathode current collector with a voltage as high as 3 V.
TUN: Can you further explain the environmental benefits of the new battery? How close could this battery put us towards our goal of sustainability?
Goodenough: Commercial batteries with this technology need to be developed by battery companies willing to license the technology. We believe that practical products can be on the market within 3 years, but the development needs to be done by industry. Our first goal, which we believe is attainable, will be a battery that can power an all-electric road vehicle that has a performance, cost, and convenience that is competitive with vehicles powered by an internal combustion engine. This development would remove the distributed air pollution choking cities and contributing to global warming. In addition, these batteries would also be able to store for the grid electric power generated by windmills and photovoltaic cells thereby reducing greatly our unsustainable dependence on fossil fuels for our energy.
TUN: If there is a finished product, and visible results, is there any validity to your skeptics’ claims?
Goodenough: The skeptics do not understand the properties of an electrode/electrolyte heterojunction, but they are correct that the thickness of a plated lithium on a cathode current collector is limited so that cathodes of large energy density will be restricted to thin films on a large surface area within a small volume. However, we have also demonstrated (yet to be published) a high-voltage cell that uses a conventional reversible insertion of the working cation into an oxide host with a capability of providing a cell voltage of up to 5 V and a long charge/discharge cycle life.
